[MEncoder-users] is this a good workflow?

Grozdan neutrino8 at gmail.com
Mon May 10 16:55:31 CEST 2010

On Mon, May 10, 2010 at 4:39 PM, Rick C. <rickcorteza at gmail.com> wrote:
> Hi again,
> I'm looking for any input regarding this workflow:
> 1.  extract the audio from original file:  mencoder original_file.mpg -of rawaudio -oac mp3lame -ovc copy -o audio.mp3
> 2.  will convert audio.mp3 to audio.m4a outside of mencoder to avoid using libfaac
> 3.  joining everything back together:  mencoder original_file.mpg -audiofile audio.m4a -oac copy -fafmttag 0x706D -ovc lavc -lavcopts vglobal=1:vcodec=mpeg4 -of lavf -lavfopts format=ipod -o new_file.m4v
> This seems to work but is maybe a horrible way to do this and that's why I was looking for some input.  Any advice is much appreciated thanks,

I'd suggest something else to avoid conversion from mp3 -> m4a which
will further degrade quality as you're going from one lossy to another
lossy codec.

1) encode with -oac pcm in mencoder. Will assure audio and video stays in sync.
2) make a named pipe with mkfifo, say 'audio'
3) run the audio encoder of your choice in the background and point
its input to the named pipe, eg

neroAacEnc -lc -br 128000 -if /path/to/pipe/audio -of /path/to/output.m4a &
mplayer yourencode.avi -vc null -vo null -ao pcm:fast:file=/path/to/pipe/audio

4) Use MP4Box to dump the video from the avi, eg

MP4Box -aviraw video yourencode.avi

5) Mux the dumped video and output.m4a with MP4Box, eg

MP4Box -fps <fps_of_video> -ipod -add video.h264 -add output.m4a -new
-mpeg4 output.mp4

> rc
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